1. Field of the Invention and Related Art Statement:
This invention relates to electronic endoscope systems wherein clear frozen pictures having few color smears can be obtained.
Recently, there is developed an endoscope imaging apparatus wherein such solid state imaging device as a CCD is provided at the tip of an endoscope, a body cavity interior is illuminated sequentially with three colors of red, green and blue, the picture image of the body cavity interior is color-imaged and a diagnosis is made on the basis of the color picture image displayed in a monitor apparatus. In this system, as it is necessary to image component picture images of three colors in order to image one color picture image, time will be taken and color smears of the picture image will be likely to be generated by the movement of the object being imaged and the hand vibration.
As a means of preventing such color smears, it is suggested in the publication of Japanese Patent Application Laid Open No. 71790/1986 to provide a means of detecting color smears of picture images on the basis of a difference between the picture images imaged at different times by an imaging means so as to control the imaging speed of the imaging means in response to the output of this detecting means. According to this prior art example, the moving speed of the imaging means will vary in response to the moving speed of the object and, even in the case of a quickly moving object, color smears will be able to be prevented from being generated.
However, the color smear preventing means in the endoscope imaging apparatus in the above mentioned prior art example is to prevent color smears in moving picture images and has no means of obtaining frozen pictures.
When an endoscope picture image is displayed as a moving picture image as it is in a monitor apparatus, in case it is desired to diagnose details, the part to be noted will move unfavorably. Therefore, there are a freezing switch directing the displaying of a frozen picture and an apparatus whereby the subsequent picture image writing into a picture image memory is inhibited by this freezing switch so that a frozen picture image may be displayed on the monitor picture surface.
In such case, in the general prior art example, when a frozen picture image is directed by the above mentioned switch, on the basis of this direction, the freezing operation of the imaging means will be made unconditionally. Therefore, in case the freezing direction is made at the time when the object and the endoscope tip position are moving relatively, a color smear will be generated on the frozen picture. As such color smear makes the natural object image hard to see, the affected part or the like will be likely to be overlooked by the observer.
There has been a problem that, in order to obtain a frozen picture in which such color smear is not generated, such complicated operation as repeating the freezing direction and freezing release until a frozen picture in which there is no color smear is obtained is required.
On the other hand, in the publication of Japanese Patent Application Laid Open No. 71791/1986, the present assignee suggests an apparatus wherein a release switch is provided so that, in case the release switch is operated, a color smear and the like of a picture image memorized in a frame memory may be detected and, in case the color smear amount is large, the color smear may be corrected to be small.
This apparatus has defects that, as it is to process picture images to correct color smears, the apparatus is so large in the scale as to be hard to apply to general electronic endoscopes and that picture images can not be corrected in the peripheral parts.